Timer



Aug. 16, 1938. r J. 1.. BARKER 5- AL 2,127,080

TIMER Filed Jan. 7, 1936 I23456 78 IOIHZ nemmzozlzwms 5 57 TE IT l8 1955555 52123 E mm Q20 05 5m: GREEN IDE QED INVENTORJ BY Joan L. bAnksn AND Hmnv A. Wucox'i Gan/M4,, m 5

A T TORNE Y.

Patented Aug. 16, 1938 UNITED STATES PATENT OFFICE TIMER ration of Delaware Application January 7, 1936, Serial No. 57,882

4 Claims.

This invention relates to a functionally and structurally improved timing device capable of use in many associations but primarily designed for use in trafflc control systems and the like.

5 Generally it is an object of the invention to provide means by which an accurately timed period, whose duration is adjustable at will, will elapse after the initiation of one action before a resulting action takes place.

An additional object is to provide a time controlled multi-position switch having a large number of contact positions independently adjustable as to timing for timing a plurality of operations or signalling indications in sequence.

Another object is to provide electrical timing apparatus of this character in which a compensation is provided in the design of the timer for the effect of line voltage fluctuation on the accuracy of timed periods.

Still another object is to provide an electrical timing apparatus in which an adjustment may be made while constructing said apparatus to eliminate errors in the periods timed due to improperly rated individual standard parts used in said 25 apparatus.

Another object is the provision of a timer in which the timing is accomplished through variation of the voltage between cathode and anode of a multi-electrode gas discharge tube and the timing is adjusted by varying the voltage between the cathode and a grid in said tube.

A further object is the provision of a timer in which the timing depends on the charging of a condenser to the gas breakdown voltage of a multi-electrode gaseous discharge tube and in which the breakdown voltage and corresponding timing limit can be adjusted by varying the negative bias of the grid in such tube.

Another object is to provide a multiple posi-. tion time controlled switch for controlling traffic signals through a cycle of right of way indications for a plurality of interfering traflic lanes in which the standard switch design can be retained while a considerable number of changes in the sequence of right of way indications can readily be made by interchanging wires or connections on one or more contact positions.

Another object of the invention is to provide a timing apparatus of the above character having a minimum number of moving parts and electrical parts and comprised of standard units operable for long periods free from mechanical and/or electrical difliculties.

With these and other objects in mind reference is now had to the following description of the device and operation thereof, and to the accompanying drawing which shows an embodiment of the timer in a trailic signal controller for use at the intersection of interfering traiiic lanes in systems of the trafllc actuated type.

A system of this character may be composed of three parts: a vehicle detecting or responsive device arranged to detect trafilc approaching on the cross street vehicle lanes, a signal control mechanism comprising the timer device, and a right of way indicating device to inform traflic in the intersecting lanes when to go and when to stop.

The vehicle actuated means or detecting device may be any of several types. It may satisfactorily be a mechanical switch, or light or sound sensitive means, or electro-magnetic, or electrostatic or other means.

A signal device for indicating right of way to the several lanes may be composed of conventionally colored green or go, amber or caution, and red or stop signal lights which are illuminated by circuits from the control mechanism.

The function of the control mechanism is to time the periods of the different signal indications and to govern changes of indications, its operation being initiated or modified by actuation of the tramc responsive devices, so that the timing mechanism and the traffic responsive devices jointly control accord of right of way.

One form of the invention will be described in detail in connection with the accompanying figure of drawing which illustrates a signal control apparatus and a circuit diagram thereof for governing the changes and duration of signal indications to the intersecting traflic lanes, and which operates in conjunction with vehicle detectors, as will be disclosed herein. This con-- trollcr is particularly designed for installation at the intersection of two tramc lanes of unequal density. It will be appreciated from the following description, however, that with alterations in the design familiar to those skilled in thegart a controller embodying these new features may be constructed for the control of traflic at many other types of intersections, as, for example, intersections where both lanes bear approximately equal traflic densities or intersections where more than two traflic lanes converge or cross one another.

For purposes of simplicity, the disclosure of the new features of the controller herein will be made in connection with apparatus of the first mentioned type, namely, one for the intersection of a major traflic lane with a cross or minor traflic lane having a lesser amount of traffic than the major lane.

A traffic signal controller constructed according to these general principles may be comprised of a timing mechanism, controlled by the trafiic responsive devices in the cross lane, and a switching device, and so arranged that the timing mechanism advances the switching device through a predetermined sequence of signal indications. If the controller is to operate from alternating, current mains, rectifying means are provided for'supplying direct current for operation of the timer.

The switching device may be comprised of a telephone rotary type line switch or stepping switch of ordinary design and conventionally shown herein. In the figure a switch of this type is shown having six contact banks A, B, C, D, E, F, of 25 contacts each, and having pairs of rotatable contacting arms or wipers, 44-49 which are advanced step by step cyclically by a magnet 88 which actuates the wipers through suitable pawls and ratchet (not shown). Upon a cycle of energization and de-energization oi the magnet the wipers are advanced one contact position. When one wiper of each pair moves off the 25th contact of the semicircular bank of contacts, the outer wiper of each pair engages the No. I contact, so that the stepping of the wipers through their cycle may be continued indefinitely. Wipers on banks A, D, E, and F, are of the bridging type, that is, they are so designed that when stepping from one contact to the next they will momentarily engage the latter before they are out of engagement with the one from which they are passing, and thus their circuits are held closed during the movement. In the figure the wiper arms of the line switch are represented by arrows, which for illustration are shown herein in the llth contact position. Y

During the rotation 01' the wipers through one complete cycle of 28 contact positions, the signal display goes through three complete cycles of indications for the control of trafiic movement. Positions I through 8 comprise the first such cycle; positions 8-l8 the second, and l|--25 the third. Wear on the rotatable shaft on which the wipers are mounted is thereby reduced proportionately. It will be noted that since the 25 standard contact positions are not evenly divisible by three, the period or the extra contact position for instance position 28, included in the third cycle, is arranged to be of veryv short duration in order that the third cycle will correspond to the others. Obviously, additional contact banks and wipers might be employed, and a line switch with more or fewer contacts in each bank may be used if desired, in order that different signal cycle configurations be obtained. Further, the contact positions might be rearranged, some special signal might be displayed in one or more positions, or a greater or lesser number 0! signal cycles during one cycle of the line switch wiper arms might be incorporated.

The timing apparatus may include a threeelectrode gaseous discharge tube or electron discharge. tube, a condenser connected between the plate and filament thereof, a source of direct current for charging said condenser and for providing a small grid bias, resistance in the charging circuit 01' the condenser, and a terminating relay operated at the end of the timed interval.

When the present timer is connected to an alternating current supply, direct current for use in the timing circuit may be obtained therefrom by any of numerous well-known means of which one is disclosed here for illustrative purpose.

Rectifier tubes 32, 33 supply'unidlrectional current from secondary coils of transformer 84 to leads 35 and 38, and a filter condenser 31- maintains a near constant voltage value. A potentiometer 48 is connected between said leads. intermediate point on the potentiometer is grounded by leads H, 38, and the end of the potentiometer marked, positive is connected by wiper 45 to bank B of the line switch, thence over one of a plurality of timing resistances -56 to complete a charging circuit over lead 51 to timing condenser 58. By lead 58 and the coil of relay 68 the positive side of the condenser is connected to the plate ii of three-electrode tube 18, and by leads 8i and 61 the negative side of said condenser is connected to grounded lead 88. Cathode 13 of tube 10 is also connected to ground, and may be of the indirectly heated type in which case it is heated by current from suitable taps on transformer 34. By means of suitably chosen taps 65 on potentiometer 40 which may be connected by the several leads 66 to the several contacts on bank C of the line switch, wiper 46 controls the grid bias or tube 10 for each contact position, but the grid potential is substantially constant withineach timing position. Wiper 48 is connected to the grid", and a condenser II is connected between the grid and grounded lead 30.

By means of armature 15 and contact 18 on terminating relay 60, circuit may be completed from lead 61 over leads i8, 19, to energize rectifier 80, which may for example be of the dry or copper sulphide or copper oxide type. This rectifier when energized supplies current to operate motor magnet of the line switch. A condenser 8| across the output oi the rectifier lessens the intensity of current fluctuations therein. Energization and de-energization of magnet 85 causes the pawls and ratchet of the line switch to advance the wipers on each bank one contact posi-- tion. In the energized position of magnet 88 a discharge circuit Ior condenser 58 is completed through low resistance 86, armature 81, and contact 88, for resetting said condenser to time the next interval.

Following is a table of wiper contact positions ,and corresponding signal periods timed in such positions:

Wiper contact position Signal period Cycle 1 Cycle 2 Cycle 8 Artery green minimum 4, 5, 6 l2, l3, 14 20, 21, 22 Artery green (skip position) a Artery green rest. 7 15 24 Artery yellow. 8 18 28 Side street room. 1 9 17 Side street green memory..- 2 10 13 Side street yellow 3 11 10 Operation of the signal controller in controlling the signals through a cycle of indications, i!

gage contact 98 and current will flow from lead 3| through lead 96, armature 99, contact 98 lead 91 and side street red light I I9 to AC ground 36, also from lead 96 through armature III'I, contact I08, lead I09, armature III, contact IIII, artery highway green light II to AC "ground 30. The tramc signal will accordingly display green to the artery traflic and red to traflic on the cross lane.

From the rectifierunit 32, 33, meanwhile power is supplied to the potentiometer 40, and over con tact #4 on bank C and wiper 46 a negative bias is maintained on the grid I2 of tube III, so that no current flows in the plate circuit of the tube. From the positive end of the potentiometer 40 and over wiper 45, contact #4 of bank B of the line switch, a circuit is completed over resistance 53, lead 51, condenser 58, and lead iii to grounded lead 30, charging the condenser at a rate which depends on the capacity of the condenser, the supply voltage, and the resistance of the circuit. Since in the present instance the first two factors are constant, only the last, the quantity of resistance, is variable and this alone regulates the rate of charging of the condenser. The latter gradually acquires across its plates a potential difierence approaching the charging voltage, this charging occuring at a rate inversely proportional to the size of resistance 53. The plate II of tube I0 is connected to the positive side oi. condenser 58 by lead 59. When the potential difierence across the terminals of the condenser has attained a certain value, the potential betweeen the plate and the filament of the tube has reached the same value, and eventually the potential therebetween is sufficient to ionize the gas in the tube; whereupon the tube suddenly becomes conducting and a current sufilcient to energize relay 60 flows.

This tube is of such a type that the potential of the grid determines the breakdown or ionizing potential of the tube, but under normal conditions of operation after discharge in the tube has commenced the grid has susbtantially no controlover current in the anode-cathode circuit. If direct current is being used in the latter circuit, the discharge in the tube normally is interrupted by opening the external anode-cathode circuit or removing the energy supply therein in some way. If alternating current is being used in the anodecathode circuit of this type of tube, the discharge will cease after the first half cycle when the current reverses. In the present embodiment where direct current is used in the anode-cathode circuit, the tube becomes non-conducting when the potential across the condenser is no longer suflicient to maintain the discharge.

From the drawing it may be seen that the I amount of bias applied to grid I2 may be changed by bank C and wiper 46, for each position of the cycle, according to which of taps 65 on the potentiometer each of the several nected. Increasing the negative grid bias in this tube increases its ionizing potential substantially proportionally. Therefore, if the timing condenser 58 were charged through the same resistance for varying grid biases, the length of the timing period would over a very considerable range vary substantially directly as the amount of negative grid bias. For this reason it is possible to utilize the grid bias in the tube to correct for errors in circuit constants of the condenser-resistance circuit and also to correct for variations in different tubes. If, for instance, in the manufacturing assembly, resistance 53 for timing the leads 66 are con-- artery green period 4 were found to be somewh highe than its rated number of ohms, which would make this period proportionately longer than the time indicated on the rheostat dial operating resistance 53, this error may be eliminated by connecting the lead from position 4 on bank C to a suitable one of taps 65 so that the ionizing potential of the tube will be decreased to compensate for the higher-than-rated' value of resistance 53.

Since raising the grid bias of the tube, which raises the ionization potential of the tube, and increasing the resistance in the condenser charging circuit both effect a lengthening of the time before operation of relay 60, it will be seen that the value of the charging resistances required for any particular timing period may be substantially reduced, if desired, by making the grid more negative in that period. The purpose of grid bias adjustment as shown in the figure is to furnish a correction to the periods timed by the charging of the condenser through the. resistances 50-56, to compensate for errors in these resistances. In lieu of having a preset grid bias and providing a rheostat adjustment of the charging circuit as shown, the arrangements could be reversed and a preset charging resistance could be employed along with a manual adjustment of the gridbias for varying the time inter- Vals.

Considering once more the operation of the timer, the energy in condenser 56 is dissipated in the circuit through relay 60, lead 59, tube I0. lead 6| embracing the condenser, when the voltage across the latter has reached the ionizing potential of tube I0 as described above. Relay 60 is energized momentarily and attracts armature 15, which-completes circuit from grounded leads 30, 61, over contact I6, leads I8, I9 to energize momentarily rectifier 80 or other embodiment of controlled power source, which supplies power to operate motor magnet 85 momentarily. Upon being energized and de-energized magnet 85 notches wipers 44-49 inclusive ahead one position into engagement with the contact #5 on their respective contact banks. By the energization of magnet 85, armature 81 engages contact 88 completing a discharge circuit for the condenser 58 through low resistance 86, so that the condenser upon recommencing to be charged in the next interval to be timed will have borne over so little residual charge that the accuracy of the next timed interval will not be adversely afi'ected, and the device will accurately measure time from the instant the charging circuit is closed.

In vehicle actuated traillc control systems of this character, vehicle actuatable devices 'in the cross lane approaches to the intersection, of wh ch dev ces one is shown in the figure as ramp I26, as well as push buttons I2I by means of which pedestrians desiring to cross the main street at the intersection may register their presence, and any other forms of detectors, may preferably be connected in parallel, and closure of any of these devices closes a circuit between leads I22, I23, completing a circuit from lead I24 thru relay I25 thence over bank'A of the line switch, wiper 44 to lead 3| for energizing the relay. Re-

. lay I25 remains energized after the momentary detector actuation by a lock-in, circuit thru lead I26, armature I21, contact I28 to relay I25. Connection thru bank A is made in all positions except the side street green interval, and as bank A has bridging type wipers this circuit locks in relay I25 until the side street green position is reached where there is no connection on bank A to lead I29 and the relay is de-energized. In this way presence of traiiic units on the side street is "remembered until right of way is accorded to the side street. In an alternative circuit for locking-in relay I25, bank A is placed between terminal I32 and relay I25 and the other side of this relay connected directly to lead 5|.

The wiper arms are now in position 5, since the momentary current through the tube I and relay 50 has caused magnet to operate, ad-- vancing the wipers. It will be noted that positions 5 and 6 are also timed by charging current to the condenser drawn through the same resistance as period 4, and connections on the several banks of the line switch are similar. If desired, a switch having fewer positions than the standard 25-contact type illustrated might be used, in which case these three positions 4, 5 and l'would be replaced by a single period timed by a resistance three times the size of resistance 50. The total length of periods 4, 5 and 5 forms a minimum period of artery green serving to permit vehicles which may have stopped on the artery during the preceding side street right of way period to accelerate and clear the intersection, and also to prevent too frequent interruption of artery right of way.

At the conclusion of each of these periods the cathode-plate circuit of tube I0 momentarily energizes relay 50 which enables motor magnet 05 to advance the wipers in the manner aforedescribed.

In period I the control mechanism rests, in the absence of actuation of the side street responsive devices, and accordingly this period may be called artery green rest position. The signal changing relays 80 and 05 remain de-energized maintaining the green light on the artery and red on the side street. Accordingly in period I when relay I25 has not been locked in by actuation of a detecting device, the condenser charging circuit from the positive end of the potentiometer 40, wiper 45, contact 5 on bank B, resistance 54, to the ondenser is open between contact I00 and arm ure I5I. However, upon the event of an actuation of one of the detecting devices, locking-in relay I25 in the manner aforebrought out, the condenser charging circuit through resistance 54 is completed over contact Ill and armature I30; the condenser rapidly reaches the voltage necessary for the plate circuit of the tube to become conducting, and the line switch wipers are notched from position 5 to position 5 by the energization and de-energization of the magnet 85. Obviously, from the above description, if a detector actuation has locked-in relay I25 before the wipers have moved into position I', the condenser-charging circuit will not rest in its open position, but will be completed through armature and the resistance 54, thus causing the period to be terminated quickly.

In position 0 connection is made on bank F through wiper 49, lead 40, relay 95, lead 5| energizing relay 05. Relay 90 meanwhile continues tie-energized. Current now flows through leads II, 55, armature I01, contact I00, and armature III, contact II2, artery yellow unit II4, while artery green unit I I5 is extinguished by breaking of the circuit through armature III and contact IIII. Side street red unit H9 remains energized as in thepreceding position. In period 8 the timing is determined by charging the condenser I50, contact Ill thru resistance 55. Grid bias is suitably adjusted by taps 65 on the resistor 40, wiper 45 on bank C. When the condenser has acquired suflicient voltage across its plates, tube I0 becomes conducting, and motor magnet 05 advances the wipers one step as described above.

Positions 9 and I0 are the side street green periods. During these periods 9 and I0 connection is made on bank E of the line switch to energize relay 90 over lead 3|, relay 90, lead 5!, bank E, wiper 40 to ground. Thus over armature 59, contact I00, lead IOI, armature I03, contact I04, a circuit to illuminate the side street green unit II! is completed, replacing the side street red I I9. Through armature I01, contact I06, lead I05, artery red unit H8 is illuminated. Timing condenser 50 will be charged through resistance 50 in period 9 and through a similar resistance 5| in period I0. Each time the voltage on the condenser becomes great enough to overcome the grid bias of tube I0, the gas in the 7 tube is ionized and the tube becomes conducting,

advancing the wipers of the line switch to their next position as disclosed above. Thus it is seen that under the condition pointed out, positions 9I0 constitute a period of side street right of way of predetermined length.

In period 9 there is no connection on lock-in bank A between lead I29 and wiper 44 and con-- sequently relay I25 is released in this period. Actuations occurring in period S'also will not energize or lock-in relay I25, thus avoiding'unnecessary wear on the relay.

It is apparent that in near-continuous traffic, or in some instances under light traflic conditions, a vehicle may arrive at the cross lane actuatable device at the end of the green period in which case it may lose the right of way before it has had suillcient time to cross the intersection. In period I0 the connection on bank A be- I tween lead I29 and wiper 44 is again established,

in order that relay I25 may now be operated and locked-in for the purpose of retaining the effect of actuations of such vehicles. The control apparatus therefore remains in such a condition that without further actuation right of way will revert to the cross lane at the endoi' artery minimum period. Since connection is made between the lock-in circuit I25 and ground over bank A and bridging type wiper 44 during all periods from this side street memory period until the next succeeding first period of side street green, relay I25 once energized will remain locked-in until right of way is granted for the waiting vehicle to cross; Period I0 is timed by the charging of condenser 58 through resistance 5| and upon the plate circuit'of tube I0 becoming conducting, the wipers are advanced in the manner already described to position I I on their respective banks.

In position II, warning of impending changes in right of way is indicated, yellow or caution 'being displayed to the side street; red to the artery. Accordingly connection is open on bank F and made on bank E, so relay 95 is de-energized and relay 90 remains energized. Thus side street green is extinguished since armature I03 breaks circuit with contact I04 and engages contact I02 completing circuit through side street yellow unit IIO. Artery red unit II5 remains illuminated by the circuit through armature I0I, contact I05. Charging circuit in this period is closed through resistance 52, lead 51. Condenser 50 will charge to the critical voltage of tube I0, as determined by the amount of negative charge on grid I2 from resistor 40, whereupon the motor magnet 85 will be energized, causing the wiper arms to advance to position I2.

By consulting the table of wiper contact posi tions and signal indications above it will be noted that position I 2 in the second cycle of signal indications is the first artery green minimum position and corresponds to position 4 in the cycle just described. Thus the condition described at the beginning of the signal indication cycle has been reached and the condenser is charged again through resistance 53, as it was in position 4. Corresponding contacts on the line switch banks in cycles 2 and 3 are connected in parallel with those of cycle I, thus on each bank, contacts I2, l3 and I4, and 28, 2I and 22 are wired in parallel with contacts 4, 5 and 5 contacts II and IS with contact 3, and so on.

One contact, No. 23 herein, is an extra position on the line switch and although on the light banks E and F it may be connected to maintain the display of artery green and side street red of preceding periods 28, 2| and 22, on timing bank B a very low resistance 56 is placed in the condenser charging circuit. The condenser rapidly reaches the critical potential of tube 10, when the notching operation will proceed again as described previously, rendering the duration of period 23 of insignificant length. Positions I5 and 24, artery green rest period, are similar to position I and may be timed through the same resistance as position 'I. The remaining positions of cycle 2 and cycle 3 correspond to those in cycle I as indicated in the above table. The arrangement of signal indications for a particular contact position is merely illustrative, and any desired arrangement difierent from theembodiment described might be used.

Under certain conditions it is sometimes desirable for a trafflc omcer to control the signal changes manually. By turning switch 88 to the "manual position the signal indicating means will display a particular indication until the button I33 is pushed whereupon the signal will change to the next set of indications in the signal cycle. This is accomplished by providing an automatic drive circuit for the line switch motor magnet, which-is interrupted in only one position of a plurality oi. successive wiper positions where no change in the signal'indications is produced. Pressing the button I33 energizes the motor magnet to advance the wipers to produce a change in the signal. The duration of each signal is \entirely in the control of the omcer, although the system still proceeds through the same cycle of colored signal indications.

When switch 58 is in the manual position, the normal circuit from lead 38 over leads I36, I38, to energize the primary of transformer 34 is interrupted, and the timing circuit is de-energized. When switch 88 is in this position a circuit embracing the rectifier 80 is completed over lead 19, contacts on bank D, wiper 41, switch 58, leads I35, I38, I35,secondary of transformer 34, rectifier 88. Assume, for example, that the wipers are engaging contact #8 on their respective banks, in which case yellow will be displayed to the artery and red to the side street. When the omcer in charge pushes button I 33, circuit is completed from ground over leads 30, I36, I34 to energize the transformer. The latter in turn energizes rectifier 88 which causes line switch magnet 85 to pull in. Upon release of the button, the transformer, rectifier 80 and magnet 85 are deenergized, causing the line switch wipers to advance to position 8, where, by connections on banks E voltage falls below'normal.

and F to relays 95 and 90, red' is displayed to the artery and green to the side street. When the button I33 is again pressed, rectifier 88 is enerlzed from the transformer over leads I35, 30, switch 88, wiper 41, contact 8 on bank D, lead 89, contact 83, armature 82, leads 18 and 18. Consequently upon energization of magnet 85, this circuit will be interrupted at armature 82, the wipers will be instantly advanced to position I0 in which the circuit to energize the magnet 85 is again completed, and upon release of the button, the subsequent release of magnet 85 advances the wipers in the customary way, to position II. This signal indication of side yellow and artery red persists until the button I33 is again pressed. Thus the rapid self-advancing circuit over armature 82 advances the wipers over all except one of a plurality of successive wiper contact positions where the same signal is displayed.

An advantage of the present timing apparatus lies in its automatic compensation in timing for variations in line voltage. Whenever the line voltage between leads 30, 3| increases, the terminal output volts of the rectifier 32, 33 will also be increased, and the potential across the potentiometer 48 will be raised accordingly. For a given rise in line voltage the voltage between grounded lead 30 and taps 65 on the potentiometer 48 will be raised proportionally. A rise in line voltage would tend to shorten the timing period because of increased voltage applied across the timing resistances to charge the condenser 58 to the fiashover potential of tube 18. With the present circuit arrangement, however, 'the higher line voltage also increases the negative bias on the grid of tube I0 thereby raising the fiashover.

potential of the tube and compensates for the increased condenser-charging rate. Corresponding compensation by automatically lowering the fiashover voltage of the tube occurs when the line This compensation will keep timing errors at a low value for substantial line voltage variations.

It will be understood that the electrical timing apparatus embodying this invention may readily be adapted to uses other than in the trafl'ic control system embodiment shown, and described herein.

From the foregoing it will be seen that the present invention provides electrical timing means for accurately timing periods whose duration is adjustable at will, and said timing means being so designed that variations in line voltage will be compensated for so that the accuracy of the timed periods will be maintained to a. high degree in spite of these variations. It will also appear that by means of the present invention a traflic control system comprised of traffic actuatable control means, signalling means, and controlling means composed essentially of a rotary type step by step switch and a timing apparatus of the above character is provided which will govern the passage of traflic through an intersection in an efficient manner for several different conditions described.

It will be understood that the above description and drawing is illustrative of but one embodiment of the invention and that variations in the construction or changes in the arrangement of the parts may be made without departing from the spirit of the invention as defined in the claims.

We claim:

1. In a timing apparatus a rotary type switch having a plurality of positions and corresponding contacts closed in certain of the positions, an

. electro-magnet for advancing said switch from one position to the next in succession, a condenser, means for charging said condenser over a period of time, a gas-filled tube having a cathode,'an anode and a grid, and which tube has a minimum voltage for conduction between the anode and cathode determined by the potential of the grid in respect to the cathode, a circuit including said anode and cathode and a relay, said circuit paralleling said condenser whereby said circuit is rendered conducting by said tube when the voltage across said condenser has reached said minimum voltage for conduction, means operated by said relay to energize said electro-magnet, and means co-operating with some of said contacts to provide diflerent potentials on said grid in diflerent positions of the switch so as to adjust correspondingly the time periods in such positions.

2. In a timer the combination oi a switch having a plurality of positions through which it is adapted to be operated cyclically and having corresponding contacts closed in one or more of such positions, a condenser, means including a source of energy and resistance for charging said condenser, means including contacts on said switch to provide for independent adjustment of said resistance in different switch positions, a gas discharge tube having a cathode, an anode and. a grid, a circuit thru said cathode and anode including a relay and paralleling said condenser, said tube rendering said circuit conducting in response to a predetermined voltage across said condenser, means responsive to operation ot said relay to advance the cyclic switch from one position,to the next, and'means including certain of having a plurality of positions and corresponding contacts closed in certain of the positions, an electro-magnet for advancing said switch from one position to the next in succession, a condenser having one of 'its terminals connected to a power supply, means for varying the charge on said condenser between an initial value and a final predetermined value over an interval of time, a gas filled tube having a cathode, an anode and a grid, a circuit including said anode and cathode and a relay and connected between the other terminal of said condenser and the power supply, said circuit being rendered conducting by said tube when the voltage across said condenser has reached said predetermined value and said predetermined value being controlled by the potential of the grid in respect to the cathode, means operated by said relay to energize said electro-magnet,- and means co-operating' with some of said contacts to provide different potentials on said grid in different, positions of the switch so as to adjust correspondingly the time intervals in such positions.

4. In a timing apparatus a rotary type switch having a plurality of positions and corresponding contacts closed in certain of the positions, an electro-magnet for advancing said switch from one position to the next in succession, a condenser having one of its terminals connected to a power supply, means for varying the charge on said condenser between an initial value and a final predetermined value over an interval of time, a gas filled tube having a cathode, an anode and a grid, a circuit including said anode and cathode and a relay and connected between the other terminal of said condenser and the power supply, said circuit being rendered conducting by said tube when the voltage across said condenser has reached said predetermined value and said predetermined value being controlled by the potential of the grid in respect to the cathode, means operated by said relay to energize said electro-magnet, a potentiometer, a plurality of tapping points on said potentiometer connected to a corresponding plurality of said contacts, and at least one additional contact connected to said grid and co-operable with said contacts one at a time to connect different potentials on said grid in diiferent positions of the switch so as to adjust correspondingly the time intervals in such positions.

JOHN L. BARKER, HARRY A. WILCOX. 

